Hello, I have a 1967 GTO with PHS docs showing it came with the HO engine option. I am rebuilding my engine and the Q-jet is not original but I don't want to pay $1,000. for a correct code carb. My question is, on the underside of the carb, the primary butterfly should have a small hole drilled in it, does anyone know the size of the hole and does the location have to be exact?

The factory assembled '67 Qjets #7027263 (manual trans) & 7027262 (T400 usage) were both made by Carter, & both were used on the 49 state app WT & YS 350 horse engines, as well as the 49 state WS & YZ coded 360hp HO engines, as well quite a few 428 B series engines. Have had many of these original ''67 Qjets over the years, & the primary throttle blades did not have the small bleed holes in them. Have several original RA application Qjets that have this feature, I do not have a numbered set of drill bits but would estimate the hole @ 1/16". Welcome to the site.

Thanks Pinion Head for the welcome and the information. There is a GTO collector here in Maryland and when I went to his place he showed me the carb. and it had the 2 holes, that is why I was asking. Not contradicting what you said, just stating what he showed me. Another GTO guy in Maryland told me to drill the 2 holes because the HO cam will make it hard to idle without them.

There was no 350HP 400CI for 1967. The base engine was 335HP/400, 360HP/400, and 360HP Ram Air and an optional economy 255HP/400 2 barrel engine for grandma. The 350HP/400 was first available in 1968.

The carbs that had the hole in the throttle plates were found on some of the high performance engines. They had "3/32 holes drilled directly in the front of the primary throttle plates in line with the idle mixture screws." These would not be found on the '67 HO carb.

To get a better understanding of the Q-jet in order NOT to get burned on the wrong/cobbled together carb, purchase How to Rebuild and Modify Rochester Quadrajet Carburetor by Cliff Ruggles. Ton of photos and how to ID, disassemble, clean, modify, & rebuild.

Jim, I'm not sure where you are trying to go with the Firebird carbs. the early Firebird Qjets were only used on Firebirds...had the limiter tab. The OP asked about '67 400 HO GTO carbs. I incorrectly noted 350hp as the base '67 400 4bbl HP notion, FORGIVE ME, I've owned many '67 GTO's...what I was trying to convey is the '67 49 state 400 engines, code YS & YZ used the exact same carb, the #7027262 . It was also used on various '67 B series with the 428. No holes were original in the original primary throttle blades. ,on this particular Qjet, the 7027262, the original anodized alum ID plug was a bright blue. Likewise, the 49 state usage '67 WT & WS engines used the #7027263 .

Original '67 CA usage 7037262's & 7037263's were also built by Carter. Again, both were used for base 4bbl GTO & HO GTO engines...just CA emission engines. Two of my good friends are currently restoring '67 400 HO CA emission GTO's, one is a 4sod Post car. Many times, one will run across a 7037262 Service Repalcement Qjet made by Rochestor. That particular Qjet is not that valuable, & one shouldn't overpay for one.

Also own Cliff's extremely well written Qjet book, as well the much earlier Doug Roe Quadrajet book. First modded Pontiac Qjet builds i performed were over 35 years ago, when over the course of a few years ordered well over half a dozen HO Power kits from HO Racing... Finally figured out several of HO's carb recipes & how to order the same metering rods, jets, & power piston springs from local dealership.

Around '82 first began pulling divorced choke ('67-72) Pontiac V8 Qjets in yards, eventually buying them by the mid '80's @ swappers & through two rebuilder contacts. Even in the early '80's, the divorced choke Pontiac Qjets were not that easy to find on cars setting with the hoods down, even in monster country yards. Often these original divorced choke Qjets had prev been pulled, many times ending up carted off in core barrels, or setting on a dirty dusty shelf.

On the '67 Carter built Pontiac V8 application Qjets, one has to be careful, there were reproduction alum tags which came avail just a few years ago, may still be avail today...I dont know. Not good, as several fraudsters bought them & have been creating fake '67 GTO Quadrajets.

To the OP, all I can further mention, is like Jim alluded to, often original Pontiac Qjets have been disassembled & reassembled with different throttle body's, different airhorns, also universal jetting. Many times, the '67's and '69 & '70 Pontiac V8 Qjets have had the '68 vac port added to the passenger side of the throttle body. Nearly all manual trans Qjets that made it to mass rebuilders gained an oversized port for an AT carbs Vac modulator line. With the right processes many of these problem issues can be remedied. Hope this helps.

What is the difference between a 702 and a 703 QJet?
I have an extra 703 for '67 with A.I.R, is it just the extra vacuum port or are there other differences?
I bought the extra one and rebuilt it using Cliff's book to have one to run while waiting for Cliff to rebuild mine and to have it in case it was lost or damaged in shipping.
Second question what is it worth?
I am still running it and the one Cliff rebuilt is on the shelf since this one is working so good I haven't bothered to swap it yet.

'67, feel free & remove the throttle body & center punch and drill the small hole in each primary throttle blade. Whether that helps, too far to say if its an instant fix. Have no idea what Qjet you are attempting to use, or it's internal circuitry.

Eric, the main differences in the #7027262 & the 7037262 is in the factory assembled airhorn & corresponding float bowl. There has to be a difference in air bleeds or emulsion tubes. I'd have to have an original of each in front of me to disassemble & carefully examine. The 49 state & CA spec Qjet use the same jets (70's), but one step richer primary rod (a 40 versus a 41) on the CA emission 70737262. The slight extra enrichment on the primary side must have something to do with helping with complete combustion with the addition air provided on the exhaust side of the chambers of the heads by the AIR galley/pump. The power piston spring as well as the secondary rods are the same (secondary rods: BF's) '67 CA emissions Pontiac V8 engines typically used a different distributor with slightly different advance curve.

PH:"Jim, I'm not sure where you are trying to go with the Firebird carbs. the early Firebird Qjets were only used on Firebirds...had the limiter tab. The OP asked about '67 400 HO GTO carbs.

PJ: Yes, the OP did ask about the '67 400 HO GTO carb, so not sure where you were trying to go with the 428 B series Qjets? So figured I might as well clarify and list all carbs having the correct ID number. That's what this forum is all about, information, not dis-information.